Other: add testing docs

docs/README.md

@@ -159,3 +159,8 @@ For more information see [custom commands documentation](custom.md)
 - [flow: feature/release/hotfix publish](flow.md#flow-featurereleasehotfix-publish)
 - [flow: feature/release track](flow.md#flow-featurerelease-track)
 - [flow: feature pull](flow.md#flow-feature-pull)
+
+
+## Package Testing
+
+Check the implementation details of the [tests](testing.md).

docs/testing.md

@@ -0,0 +1,32 @@
+# Package Testing
+
+We try to cover the most crucial functionality with unit tests using
+[UnitTesting](https://github.com/randy3k/UnitTesting). To run the tests
+locally, you should install UnitTesting via Package Control.
+
+## Run the test specs locally
+
+First you need to [clone](https://github.com/divmain/GitSavvy#less-simple) GitSavvy repo from source.
+Open the directory `GitSavvy` and simply run the command `UnitTesting: Test Current Project`
+
+## Some details about DeferrableTestCase
+
+[DeferrableTestCase][1] is used to write the test cases. They are executed by
+the [DeferringTextTestRunner][2] and the runner expects not only regular test
+functions, but also generators. If the test function is a generator, it does
+the following
+
+- if the yielded object is a callable, the runner will evaluate the
+  [callable][3] and check its returned value. If the result is `True`, the
+  runner continues the generator, if not, the runner will wait until the
+  condition is met.
+
+- If the yielded object is an integer, say `x`, then it will [continue][4] the
+  generator after `x` ms.
+
+- Otherwise, the `yield` statement will always wait for 10 ms.
+
+[1]: https://github.com/randy3k/UnitTesting/blob/dc810ee334bb031710b859478faaf50293880995/unittesting/core/st3/runner.py#L49
+[1]: https://github.com/randy3k/UnitTesting/blob/dc810ee334bb031710b859478faaf50293880995/unittesting/core/st3/runner.py#L7
+[2]: https://github.com/randy3k/UnitTesting/blob/dc810ee334bb031710b859478faaf50293880995/unittesting/core/st3/runner.py#L49
+[3]: https://github.com/randy3k/UnitTesting/blob/dc810ee334bb031710b859478faaf50293880995/unittesting/core/st3/runner.py#L57